This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Approximately 20% of infants who die of sudden infant death syndrome (SIDS) die while in child care settings, and many of these deaths occur in the first week, particularly on the first day of day care.3, 4 While no single factor accounts for all SIDS cases, there are several possible factors that contribute to increased SIDS risk during the transition to child care;these include change/disruption in sleep pattern,5 increased stress in the infant,1 and disruption in the normal maturation of the infant circadian rhythm.6 While our ultimate goal is to investigate specific factors that may increase SIDS risk in infants at the time of transition to child care, the central goal of this pilot study is to describe the changes in sleep patterns, markers of circadian biorhythm, and markers of infant and parent stress associated with child care entry. We will collect critical information to be used to generate hypotheses and conduct sample size and power calculations for the development of an R01 application to investigate mechanisms that may increase SIDS risk in infants at the time of transition to child care. No previous studies have examined sleep disruption in infants associated with the transition to child care. We will address the following specific aims: 1. To describe sleep patterns in infants as they transition from home to child care, including 24-hour sleep duration, changes in the timing of daytime naps, and changes in nocturnal sleep periods. 2. To describe, in home and child care settings, potential sleep disrupters, such as temperature, light and noise, that may impact sleep quality and sleep patterns. 3. To describe markers of parent and infant stress during the transition to child care. 4. To describe markers of infant circadian biorhythm during the transition to child care.